Proximity sensors are employed to detect the presence or absence of an object that appears within a given distance of the sensor. In one example, a proximity sensor can detect when an object, such as a user's face, is within proximity of a cell phone. If user detection is determined, interface inputs on the phone can be disabled when the person is talking so that contact with the user's face does not inadvertently select an input while talking. Proximity sensors can utilize various electromagnetic properties such as light, acoustics, inductance, or capacitance to detect objects. Proximity sensors that utilize light typically employ a light emitting diode (LED) that emits light toward an object, which is reflected and then received by a single photodetector to detect the presence of the object. In some applications, the light must be transferred and reflected through a protective optically transparent covering, such as through the glass cover of a cell phone, for example.